Is it any good?
Where? in which country/state?
depends on the subject ofcourse!!
Masters... regular or private both serve the purpose... Regular masters is considered better cos of the the more information you can gather through the collegues as well lectures which are the important element of studying.
I have done my masters as a Private candidate, without any sort of guidance from anyone. And it was a hard thing to do.
But as far as the value of the degree is concerned, there is no difference. The difference is just that doing it Private is a bit harder and normally one does not get as good a result as one will get as regular student. 